Fix incompatible encoding issue

When `address` is an UTF-8 string, using it together with the ASCII-8BIT `json` in the same string raises an exception: _"incompatible character encodings: UTF-8 and ASCII-8BIT"_.

Instead of mucking around with the encodings, this commit simply splits the log message into two parts as a quick fix.

Adding a test for this would mean overhauling the build environment, mocking `call_geocoder_service` etc. If you're interested I'd be happy to do that and send another pull request.